165463 - Stack fails to redraw properly after a child node is shrunk

Status: NEW

(Core :: XUL, defect)

Description

[Paul Clifford]

User-Agent:       Mozilla/5.0 Galeon/1.2.5 (X11; Linux i686; U;) Gecko/20020607
Build Identifier: Mozilla/5.0 Galeon/1.2.5 (X11; Linux i686; U;) Gecko/20020607

The stack-redraw-bug.xul page has a box inside a box, inside a stack.  The inner
box is larger than the outer one, but is not visibile by default ("visibility:
collapsed").  The outer box has a CSS rule (".bug-outer:hover .bug-inner {
visibility: visible }") to make the inner box visible when the pointer is held
over it.  The outer box expands and shrinks as expected, but when it shrinks it
doesn't redraw the area it used to cover.

Reproducible: Always

Steps to Reproduce:
1. Load the page into Mozilla.
2. Move the pointer over the box, causing it to expand.
3. Move the pointer out of the box, causing it to shrink.
Actual Results:  
The area to the right of the original, smaller, box is not redrawn.

Expected Results:  
The area enclosed by the larger box should be redrawn after it shrinks.

The same bug also occurs if the stack element is replaced with a bulletinboard
element.

Comment 1

[Paul Clifford]

Attachment: A local copy of the stack-redraw-bug.xul page

Comment 2

[Paul Clifford]

Attachment: A local copy of the stack-redraw-bug.css page

Comment 3

[Boris Zbarsky [:bzbarsky]]

compositor.

Comment 4

[Paul Clifford]

Attachment: Simple standalone demonstration of the bug

Move your pointer over the box and it expands, move the pointer out of the box
and it shrinks.  After it shrinks the area it used to cover is not redrawn.

Comment 5

[Paul Clifford]

Attachment: Patch to fix the redraw bug

This patch fixes the problem for me.  It looks as though the
nsStackLayout::Layout method only redraws the area when a child node is moved,
not when it resizes.

Comment 6

[Paul Clifford]

Attachment: Corrected patch

The previous patch was a bit hasty, this should be correct.

Comment 7

[Olivier Cahagne]

Has patch and testcase, marking NEW.
However, does this still happen in 1.4a (trunk) and does the patch work with a
current trunk ?

Comment 8

[Paul Clifford]

I've verified that the bug is still present in the most recent trunk build, id
2003031208.  The CVS log shows only one minor change to nsStackLayout.cpp
(removal of an #include) since the patch was made, so it should still be valid.

Comment 9

[Kevin McCluskey (gone)]

-> XUL

Comment 10

[Kevin McCluskey (gone)]

-> XUL Owner